nuttcp: add tarball hash

Fixes (eventually, once the bad downloads are deleted):
http://autobuild.buildroot.net/results/055/0556ffec533af65392c24f7c74092d3282245c95/
http://autobuild.buildroot.net/results/481/4810de845bac9ec28cba86379de0f8c554038ea0/
http://autobuild.buildroot.net/results/384/384b627a104793f460072aa43381a8c2d703a693/
http://autobuild.buildroot.net/results/2f8/2f8574a5bc692e3dfb803b420fb6ae2dc420cfed/

And many others.

There's no upstream hash, but this matches E.G. Freebsd:

http://lists.freebsd.org/pipermail/freebsd-ports-bugs/2009-August/170685.html



Signed-off-by: Peter Korsgaard <peter@korsgaard.com>